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Re: Mobo with fan controls

On Son, 2004-02-01 at 17:25, Antonio Rodriguez wrote:

> Your hints will be welcome

Ok.... :)

Well, the general layout would be clear at a glance if I had a digicam.

I made three big holes into the side of my case, close to the bottom.
Here's where the fans blow air into the case. The fans don't need
to be special, really. But one should have a tacho line to connect to
your mobo.
Then I made a simple wooden frame onto the outside of the side panel,
and that's the place where I attach the 'dust filter' (actually the
filter is meant for ... ahm... 'air exhaust in kitchen, above cooking
station'). The idea was if the filter surface is bigger, so the fan's
wouldn't go full throttle just to overcome the filter's air resistance.

Some stab at ASCII art (cough):

|          |
|   case>  |
|          |
~          ~

~          ~
|          |
|          |
| <dust    |
|          |FAN->
| <fil-     FAN->
|           FAN->
| <ter      FAN->
|           FAN->
|           FAN->
|           FAN->
|          |FAN->

Thus, the filter has a large surface (40x50cm) and there is some
distance between the filter and the actual air inlet. I had to place
an upright wine cork into the center of the filter, otherwise it would
be drawn to the case.

It looks ugly; however, I've got it under the desk with the modyfied
side to the wall. It also wasn't easy to make the holes; if I had do it
again, I'd give the job to a blacksmith or whoever.

Now the tricks... you've got to make sure that the PS fan won't shove
more air out than the case fans draw in; otherwise, you'd still get some
amount of unfiltered air into the case. I did so by going over the power 
supply as well:

  _____________                  __FAN________
<-|fan        |                  |           |
<-|fan  before|                  |   after   |
<-|fan        |                  |           |
  -------------                  -------------

Yes, the PS actually spills it's hot air back into the case.

You als need to close most of the air inlets and other holes in the
lower half of your case. I found out that the air flow would pass
straight through the case and leave it on the other side, with little
fresh air reaching the PS and drives in the upper half.
Before I did so, I had a super-cool mobo and harddisks, with the CD-Rs and
power supply revolving the same air over and over again. Now the cool air
is forced up, and the hot air pushed out.

Finally, the ciruitry to make your fans temperature-controlled. Unfortunately,
I have not yet found a satisfying solution: all cicuits have too large a
temperature span. They regulate from barely moving to full throttle over
a range of 60 C -- that's far too much for a computer.
Ideally, it would start spinning at ~15 C (a temperature I hardly expect
to ever have in my office) and would go full speed at 40 C (which many
hardware manufacturers name as safe maximum).
If somebody knows hot to build such a beast, please let me know.

Things being as they are, I frequently have to recalibrate my setup according
to the current climate. It's a good idea to have the cicuit outside of the
case, so you can calibrate and readjust without disturbing the setup.


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